In a high-resolution measurement device, an overload, particularly, an impact load in which a great load is impulsively applied has been known as a first factor for hindering accurate weighing. Conventionally, as measures for cushioning and absorbing the impact load, shock absorber mechanisms using elastic members such as coil springs or rubber have been proposed (refer to Patent Literatures 1 and 2). These shock absorber mechanisms use a method in which a kinetic energy is absorbed as an energy the coil springs or rubber has, and are thus effective for static overloads.
However, recently, weighing work by automatic machines has increased, and an operation using a motor or pneumatic equipment as a driving source is performed in the case using an automatic machine, and thus as compared with manual weighing work, an impact load in which a load ranging from a few times to a few tens of times is impulsively applied is produced. Because this impact load is transmitted at high speed, in the conventional shock absorber mechanism using the method in which a kinetic energy is absorbed as an energy the coil springs or rubber has, in which the pan position is mechanistically lowered by using a set load of coil springs or rubber, there has been a situation such that the impact cannot be sufficiently absorbed to disable appropriate weighing, and the measurement device, particularly, its sensor unit cannot be protected, so that the sensor unit is sometimes destroyed.
Moreover, a second factor for hindering accurate weighing of a high-resolution measurement device is charging of a measuring object. When the mass of a measuring object is measured, if the measuring object is charged by static electricity or a measurer himself/herself is charged by static electricity, accurate weighing can no longer be performed as a result of charging with static electricity. That is, when static electricity builds up in a weighing pan, lines of electric force are generated between the pan and a case that supports the pan, a force by the static electricity acts in the direction of the lines of electric force, the force by static electricity interferes with a measurement value, and the measurement value changes with an elapse of the discharge time of static electricity in some cases. In particular, in an indoor environment, such as a clean room or a constant temperature room, in which an air conditioner is continuously operated, it often becomes a low humidity of 20% or less, and a charging phenomenon occurs with the low humidity, and accurate weighing can no longer be performed due to the charging phenomena in some cases.
Therefore, methods such as inserting an electrical resistance element having an ohmic value between the pan and pan receiver or inserting various metallic conductive components such as plate springs and other springs between the pan receiver and pan have been tried. However, these techniques, in which an additional component(s) is required for adding an anti-static function and the additional component(s) serves as an obstruction during cleaning, are thus not sufficient for simplification in structure for even suppressing phenomena resulting from charging with static electricity. Therefore, as an arrangement for eliminating these drawbacks, there has been a proposal that projecting pieces of a plate spring fixed to a pan receiver are penetrated through pan receiver legs supporting the pan and are brought into contact with the pan (refer to Patent Literature 3). However, indeed this proposal is effective as a measure in the case where a pan is charged with static electricity, but similar to the conventional shock absorber mechanisms, the arrangement in which protruding pieces of a plate spring are brought into contact with a pan does not serve as a solution for the foregoing first factor.